going from 98 to XP

I've been wanting to get into capturing video and working with video
and DVD, but Windows 98SE doesn't seem to want to handle it very well,
so I'm thinking of going to XP.
1. If I install over 98, am I still going to be stuck with the same
problems or will XP cover up all the disadvantages I'm having with 98?
2. What about all the programs I have installed, will they now work
with XP even though they are not XP programs since 98 is still there
somewhere?
3. Am I asking for more headaches by installing over 98 instead of
doing an install on a clean hd? I would like to keep all the programs
I've collected over the years.
4. What are the advantages and disadvantages of getting the OEM
version?

Thanks for your help,
eddwnn